“Raise the Wage! $9.50 by 2015” exclaims this year’s billboard atop the AFL-CIO pavilion at the State Fair. It’s getting a positive response — better, said several volunteers in red T-shirts bearing the same logo, than labor’s more controversial 2012 State Fair theme, “Tax the Rich.”

That may be in part because fair­goers understand another message, the one on the black T-shirts sported by a number of participants in Tuesday’s “Raise the Wage!” campaign kickoff news conference: “Increase family income, improve child outcomes.”

They pointed to data that refute the common misconception that few heads of households are paid the minimum wage. In Minnesota, a third of 360,000 minimum-wage workers are either parents or are married.

The proportion of heads of households is likely higher among low-wage workers whose wages are only slightly above the minimum, and would likely move up along with it. A national study released last week said that if the hourly minimum were increased to $10.10, a quarter of those whose incomes would grow are parents.

To underscore the point, three such breadwinners spoke at the campaign kickoff. A Target grocery stocker told of regularly skipping supper so her children could eat. A Target janitor fretted that his children won’t be able to afford college. An airport wheelchair assistant said he can’t pay his family’s bills on $7.25 an hour with no benefits.

“Economic security of families is critical to the health and well-being of our children in Minnesota,” said Peggy Flanagan, executive director of the Children’s Defense Fund of Minnesota, the organization behind the black shirts. “A parent working full time earning the federal minimum wage has a gross annual income of roughly $15,000. This falls far below what is needed to meet basic needs — housing, food, health care, transportation and child care.”

MAJORITY SUPPORT

A mid-May poll by North Carolina-based Public Policy Polling found that a 54 to 37 percent majority of Minnesota registered voters favored an increase in the minimum wage to $9.50 an hour.

Flanagan cited a 2011 Brookings Institution study that found a strong link between household income, particularly during a child’s preschool years, and children’s academic performance. As little as $1,000 more in annual income made a small but statistically significant improvement in children’s school scores, it found.

Emphasizing that connection is smart strategy for the labor-led drive to convince the 2014 Legislature to raise the state’s minimum wage, as the 2013 Legislature seemed poised to do until talks over competing measures broke down in the session’s final days.

A state that touts its well-educated workforce as its strongest economic asset should be ashamed of being one of only four states — along with Georgia, Wyoming and Arkansas — with a state minimum lower than the federal $7.25 an hour. This state should lose that distinction and phase in a higher minimum over several years. (The federal floor applies to employers engaged in interstate commerce. For those that don’t, Minnesota’s minimum is $6.15 for larger companies and $5.25 for small ones.)

Advocates of a wage hike make other sound arguments. They point to the inherent worth of work; the boost in consumer spending that a minimum-­wage hike would trigger, and the desire for full-time workers to be self-sufficient rather than dependent on taxpayer support for life’s necessities.

Christy Main, a Washington County human-services employment counselor, said she used a vacation day to work at a “Raise the Wage!” kiosk at the State Fair because of the good it would do her clients. Two-thirds of them work at minimum-wage jobs, “and they still qualify for cash and food assistance. They don’t make enough to support their families,” she said.

The kickoff of a larger push for a minimum-wage increase in 2014 came one day after the release of the latest K-12 Minnesota Comprehensive Assessment scores. They showed little progress statewide in closing an achievement gap of long standing. Though that gap is often described in racial terms, it’s also a gap between children from economically secure vs. insecure households. Persistent poverty and persistently low test scores go hand-in-hand.

With growing numbers on the low side, the achievement gap is wide enough to trip up this state’s economy in the not-distant future. The “Raise the Wage!” campaign should help lawmakers see a higher wage floor as a significant element in Minnesota’s public-policy strategy for student ­success.